1. Technical Field
The invention relates to the transmission and receipt of electronic mail in a computer environment. More particularly, the invention relates to the time and date stamping of electronic messages and commerce using a trusted entity across a computer network.
2. Description of the Prior Art
Electronic mail (email) services have become heavily relied upon in the business and private sectors. The use of email has dramatically increased in the last few years. However, one feature that has been missing from the current email systems is a trustworthy time stamp for email messages and electronic commerce. Time sensitive messages and transactions could be then transmitted electronically rather than through conventional mail. Such a time stamp would have to be trusted so the recipient can trust that the time and date on the message is accurate and has not been tampered with.
Generally, a computer's date and clock parameters are easily modified by unprivileged users. These date and clock settings are used to tag electronic messages and commerce. There was no way to trust the time and date of a message even if it was signed and/or encrypted.
One approach to this problem uses a centralized, proprietary mail system. It requires the sender to send the document that requires the time and date stamp to a central server. The server receives the document and stamps it with the current date and time and attaches the digital signature of the post office. The digital signature is used to indicate if the message has been tampered with. If the signature is invalid when the message reaches the recipient, then the message has been tampered with.
The resulting message is routed to the recipient. The recipient is required to have a proprietary mail reader installed on his computer that contains a public key that is used to decode the document. The U.S. Postal Authority approach allows any recipient that has the mail reader installed on their computer to open any mail even though it was not intended for the recipient because only one public key is used across the system.
The sender's documents are archived at the server's location which is meant to provide some redundancy for the sender, but allows for multiple copies of the sender's document to exist and possibly be breached. The sender's privacy is not assured using this approach.
Although most Internet browsers use a standards based mail system (Simple Mail Transfer Protocol (SMTP), Post Office Protocol (POP), Hypertext Markup Language (HTML) embedded in the Multipurpose Internet Mail Extensions (MIME)) which are easily readable by third parties, this approach is proprietary and closed. It has a top level trusted authority (the U.S. Postal Authority) and the architecture is very flat; the user has to deal directly with the authority. There is also no trust hierarchy which reduces the scalability of the system.
It would be advantageous to provide a time stamp authority hierarchy protocol and associated validating system that integrates with the security system of the user's Internet browser and a standards-based mail system while transparently allowing the user's local server to time stamp the user's messages. It would further be advantageous to provide a time stamp authority hierarchy protocol and associated validating system that does not require that the recipient have a specialized mail reader.